TL;DR: In Lục Hào, a moving line is a line cast in the "old" group (three coins on the same face), and each moving line flips into its opposite line to produce the changed hexagram. The reading method according to Tăng san bốc dịch: take the original hexagram and the moving lines as the basis for identifying the useful spirit and judging good or bad fortune; the changed hexagram is used only to examine which line a moving line changes into, and whether that changed line generates or controls back against its own moving line, not to generate or control the other lines. The changed hexagram does not replace the original hexagram; it is a layer of information about the direction of change and the later fate of the matter.
What are a moving line and a changed hexagram?
A moving line is a line that comes out in the "old" category when casting: three coins all showing the back (old yang, symbol ○) or all showing the character face (old yin, symbol ×). According to the Chiêm quái pháp section appended to Tăng san bốc dịch, one back and two character faces is "đơn", drawn as a solid line; two backs and one character face is "sách", drawn as a broken line; three backs is "trọng", drawn as ○; three character faces is "giao", drawn as ×[1]. Only the two kinds ○ and × are moving lines. Six tosses from the bottom up give a six-line hexagram, called the original hexagram.
The changed hexagram is the second hexagram built from the original by flipping each moving line: ○ (old yang) flips into a broken line, × (old yin) flips into a solid line, while the lines that do not move stay as they are. Tăng san bốc dịch states plainly: "六爻不動則不變，動則必變", meaning that if the six lines do not move the hexagram does not change, but once there is movement there is certainly change[1]. The example the book gives: in the single trigram Càn (three solid lines), if the bottom line moves, that line flips from solid to broken, and Càn changes into Tốn[1].
A distinction is needed: the original hexagram is the present situation, while the changed hexagram is the direction the matter is turning toward. The two exist together and do not replace each other.
Which hexagram does the original change into?
The rule for flipping lines is purely mechanical and does not depend on the meaning of the hexagram: simply look at which line carries ○ or × and flip that line, leaving the rest unchanged. The number of moving lines can run from one to six. If one line moves, the changed hexagram differs from the original by exactly one line. If all six lines move, the changed hexagram is the opposite hexagram of the original (yang lines become yin, yin lines become yang).
| Original hexagram | Moving line | Changed hexagram | How it flips |
|---|---|---|---|
| Single trigram Càn (☰) | Bottom line ○ | Single trigram Tốn (☴) | Bottom line turns from yang to yin |
| Single trigram Càn (☰) | Top and bottom lines ○ | Single trigram Khảm (☵) | Top and bottom lines turn from yang to yin |
| Single trigram Khôn (☷) | Middle line × | Single trigram Khảm (☵) | Middle line turns from yin to yang |
| Single trigram Khôn (☷) | All three lines × | Single trigram Càn (☰) | Every yin line becomes yang |
| Thủy Thiên Nhu | First line, third line ○; fourth line, top line × | Thiên Thủy Tụng | First line, third line turn from yang to yin; fourth line, top line turn from yin to yang |
The table above takes its examples directly from the Động biến chapter of Tăng san bốc dịch[1]. The first four rows are three-line single trigrams, the last row is a six-line double hexagram. One point to note: the name of the changed hexagram is read from top to bottom, that is, outer trigram first, inner trigram second. For example, Thủy Thiên Nhu has the outer trigram Khảm (water) and the inner trigram Càn (heaven), read as Thủy Thiên Nhu. When it changes into Thiên Thủy Tụng, the outer trigram is Càn and the inner trigram is Khảm, read as Thiên Thủy Tụng.
In what order do you read it?
The reading order in Lục Hào is not to read the original hexagram first and then the changed hexagram as if they were two independent texts. Tăng san bốc dịch lays down a clear principle: "變出之爻能生克沖合本位之動爻，不能生克他爻", meaning that a changed line can only generate, control, clash with or combine with its own original moving line, and cannot generate or control other lines; and conversely, other lines cannot generate or control the changed line either[1].
In other words, the relationship between the original hexagram and the changed hexagram plays out only pair by pair, between each moving line and its corresponding changed line. The changed line is not an independent line inside the original hexagram, but the result of a specific moving line transforming.
The practical order has four steps:
- Step one, identify the useful god: choose the line in the original hexagram that stands for the matter being asked about. For example, asking about parents takes the Parents line, asking about money takes the Wife/Wealth line, asking about office and reputation takes the Officials line[1].
- Step two, assess fortune and misfortune on the original hexagram and the moving line: whether the useful god is strong or weak, whether it receives support or is checked, and how the moving line acts on the useful god.
- Step three, examine the changed line of each moving line: whether the changed line generates back into the moving line (returning generation) or controls back into the moving line (returning control), or transforms into an advancing spirit, a retreating spirit, into emptiness, or into the tomb.
- Step four, bring it together to fix the timing: the moment a matter occurs is usually tied to the branch, month or day markers that have a relation to the moving line and the changed line.
An example in Tăng san bốc dịch shows this reading clearly. In the month of Tý, on the day Quý Dậu, a person asked about their own marriage and got the hexagram Hằng changing into Đỉnh. The Wife/Wealth line Tuất earth moved in the response line and changed into the Offspring line Tỵ fire; the self line was the Officials line Dậu metal. The judgment: Dậu metal holds the self line, Tuất earth wealth moves to generate the self line, and self and response further generate each other; although Tuất falls into emptiness, once it moves it is not counted as empty, and the next day when it leaves emptiness the matter will certainly come through. And indeed the next day the answer came, and afterward the couple remained firm[1]. This judgment rests only on the self line, the response line and the moving wealth line in the original hexagram; the book does not bring the changed line Tỵ fire out to generate or control other lines in the hexagram.
Which lines does a changed line generate or control?
The principle that "a changed line only generates or controls its own original moving line" is stated by Tăng san bốc dịch in the chapter Động biến sinh khắc xung hợp, with the example of the hexagram Khôn changing into Hỏa Địa Tấn cast in the month of Tý on the day Mão. The top line, the Offspring line Dậu metal, holds the self line and moves, changing into the Parents line Tỵ fire, so Tỵ fire only returns to control that very Dậu metal line and does not generate or control other lines. The fourth line Sửu earth moves and can generate the Dậu metal on the self line, but cannot generate the Dậu metal line that it itself changed into, and that changed Dậu metal line likewise does not generate or control any other line[1].
But there is one important exception: the day and month. Tăng san bốc dịch says "日月如天，能生克動爻、靜爻、變爻、飛爻、伏爻", meaning that the day spirit and the month marker have the power to generate or control every kind of line, including changed lines[1]. Even in the example hexagram above, the book points out: the month marker Tý water can control the changed Tỵ fire line, and the day marker Mão can clash with the changed Dậu metal line.
In the Độc phát chapter, Tăng san bốc dịch also rejects the approach of discarding the useful god and clinging to a single moving line to decide a matter. The book holds that whether there is a single moving line or a single still line, determining fortune and misfortune and the timing must still take the useful god as the master, and cannot rest on the moving line alone[1]. This reinforces the principle: the changed hexagram is a layer of supplementary information for the moving lines, not a parallel diagnostic system.
Common mistakes
The first mistake is reading the changed hexagram as an independent hexagram. Many people look up the name of the changed hexagram in a book and then judge by that hexagram's meaning, whereas Tăng san bốc dịch uses the changed hexagram to examine which line each moving line changes into, and to examine the changed trigram (transforming into generation, transforming into control, reverse groan, repeated groan) in the chapters Quái biến sinh khắc mộ tuyệt and Phản phục, not to judge by the meaning of the hexagram name[1].
The second mistake is supposing that a changed line can generate or control every line in the hexagram. The principle already stated is clear: a changed line acts only on its own moving line[1].
The third mistake is ignoring the day and month when examining a changed line. The day and month have the power to generate or control a changed line, so a changed line can be clashed and broken by the day or month, which completely changes its meaning[1].
The fourth mistake is confusing "moving line" with "changed line". A moving line is a line in the original hexagram; a changed line is a line in the changed hexagram. The two lines sit in two different hexagrams and are linked only as a pair.
Does the changed hexagram replace the original hexagram?
No. The original hexagram remains the foundation for identifying the useful god, the self and response lines, the six relations and the overall fortune or misfortune. The changed hexagram only shows the direction of change and the later course of each moving line. In the example of the hexagram Hằng changing into Đỉnh above, the judgment "the marriage succeeds" rests on the self line, the response line and the wealth line in the original hexagram; and for the timing the book takes the day when the Tuất earth line leaves the empty period[1].
You can picture the original hexagram as a map of the current state, and the changed hexagram as arrows showing where the points in motion are heading. Drop the original hexagram and there is nothing left to read; drop the changed hexagram and you lack information about the dynamics.
A suggestion from Nhật Nguyệt
When studying Lục Hào on your own, practise in this order: write out the original hexagram in full with its six relations, five elements, self and response lines; mark clearly which line moves and whether it moves as ○ or ×; build the changed hexagram by flipping exactly the moving lines; only then judge. Do not rush to look up the meaning of the changed hexagram in a book, because Tăng san bốc dịch does not use the changed hexagram that way[1]. And always remember: this is the convention of one specific school of hexagram divination, not a scientific conclusion about human destiny.
